Plate Tectonics Flashcards
What are the four layers of the earth
- the inner core
- the outer core
- the mantle
- the crust
5 facts about the inner core
- its in the centre of the earth
- hottest part of the earth
- it is solid
- made up of iron and nickel
- temperatures of up to 5500°C
4 facts about the outer core
- surrounds the inner core
- liquid layer
- made up of nickel and iron
- temperatures similar to the inner core
4 facts about the mantle
- it is the widest section of the earth
- diameter of approximately 2900km
- Made up of semi molten rock
- upper parts its solid but near the core it is soft and beginning to melt
4 facts about the crust
- outer layer of the earth
- it is a thin layer; 0-100km thick
- solid layer were we live
- 2 types; continental crust which holds the land and oceanic crust which holds the water
How do plates move
By convection currents in the mantle- heat rises from the core through the mantle and reaches the crust as the current moves sideways it drags the plates above with it.
Hat happens at a constructive boundary
two plates move apart
They are pushed by convection currents that rise up from the mantle
They move very slowly apart, magma rises up in the gap and breaks through to form new crust
mostly found under water
The best known example is the mid Atlantic ridge
What happens at a destructive plate boundary
- continental meet san oceanic plate
- oceanic is forced under the continental plate because it is denser
- this is called subduction
- as it sinks it melts and forms magma
- the magma will be forced up through the crust by pressure and create a volcano
- best example is were the Nazca plate is forced under the South American plate
What happens at a conservative boundary
- Plates move horizontally past each other
- no crust destroyed or created
- can create earthquakes
- best example is the San Andreas fault in California
What happens at a collision boundary
- 2 plates of the same kind push into/against eachother
- buckle upwards and form fold mountains
- best example Himalayas
- frequent earthquakes
What is a volcano
A volcano is a vent or chimney that connects molten rock to the earths surface. It includes the surrounding cone of built up material
Where do you find volcanoes
Generally at plate boundary’s
constructive plate boundary
Destructive plate boundary
Why do volcanoes erupt
Volcanoes from when magma is forced up through the crust
If there are gasses in the magma they can escape as the magma gets higher up
These gasses can make an explosion
If there is old solidified lava (a plug) blocking the way out the gasses and magma either force it out of the way or breakout of the side of the volcano
At a constructive boundary eruptions are quite gentle
At a destructive boundary eruptions are explosive
What are hotspots
There are not plate margins
Volcanoes happen there
Very strong convection current forcing magma up
4 ways to predict a volcano
- when magma moves it cause hundreds of little earthquakes
- days before, magma moves up this heats the ground around it
- rising magma makes volcano swell or bulge
- gas seeps from the volcano
4 benefits of volcanoes
- ash dust and any weathered rock produces very fertile soil
- volcanic rocks are good building materials
- tourists come to see the volcanoes so money ca be made from tourist trade
- geothermal energy can be created by steam from the volcano
What is an earth quake
- an earthquake is the result of sudden release of stored energy in the earths crust.
- a wave that travels through the earth is called a seismic wave
How do earthquakes occur (5)
- plates in the earths crust move due to convection currents in the mantle.
- plates try to move past each other and can ‘stick’. - - This builds up tension and stress
- When the force of the moving plates overcomes this tension, the resistant jolt or shock causes an earthquake
- The point where the jolt happens underground is called the focus
- The point on the surface immediately above the focus is called the epicentre
Where do earthquakes occur
- generally they occur at plate boundaries
- Mainly at destructive, conservative plate boundaries
How are earthquakes measured (4)
- earthquakes measured using a seismometer.
- The amount of energy an earthquake gives out is called its magnitude
- The magnitude of an earthquake is reported using a graph called a Richter scale
- It is a logarithmic Scale which means that a size 6 earthquake on 5 a Richter scale is 10 times larger than a size 4
Immediate impacts of an earthquake (5)
- buildings collapse
- debris falling causes injury/death
- roads destroyed
- water and gas pipes burst
- electricity off
Knock on effects off an earthquake (5)
- people lose jobs
- mental trauma
- landslides
- tsunamis
- disease
How to limit the damage of an earthquake (ppp)
Plan- practice, stockpile medicine, food,blankets
Protect- construct bu;dings strong enough to withstand the shock
How are tsunamis caused
By an earthquake under the sea. Shock force makes waves on the surface which travel through the water, as the water gets shallower they get larger
